Technical Abstract:
Grazing of cool-season grasses by beef calves before entry into the feedlot for finishing is an important component of the US beef production system. The length of time in the feedlot and the quantity of feed grain required to reach market BW would be reduced if more BW was gained during the grazing season. The objective of these experiments were to evaluate the feasibility of using perennial cool-season grass in early fall and late spring to extend the winter wheat stocker calf grazing season. In Experiment 1, six 1.8-ha pastures of non-toxic endophyte infected fescue (Festuca arundinacea Schreb.) were established at the Grazinglands Research Laboratory and allowed one year of deferment for establishment. A different set of calves were used each fall (BW = 250 ± 44 kg) and spring (BW = 326 ± 34 kg). Calves were randomly assigned to pastures and stocking rate was based on the amount of forage available for grazing. Pasture was the experimental unit and data were analyzed using PROC MIXED procedures with year being random. Pastures were grazed for 38 ± 7.4 d in the fall (mean start date = Oct. 22) and for 33 ± 6.2 d in the spring (mean start date = Apr. 23). Average daily gain (0.56 vs. 0.99 kg) and stocking rate (1460 vs. 2200 kg BW/ha) was lower (P = 0.03) in the fall than in the spring. In Experiment 2, 144 Angus steers were divided into 6 groups, and grazed on 2.1-ha fescue pastures (n=6) for 29 d in the fall, a common wheat pasture for 134 d in the winter and spring and returned to fescue pastures for 29 d in late spring. Initial BW (Nov. 14) in the fall was 248 kg. Steers gained 19.7 ± 1.5 kg in the fall on fescue, 118.0 ± 2.6 kg in the winter and spring on wheat pasture and 32.1 ± 1.7 kg in the late spring on fescue. We conclude that fescue pasture can be used in a sequence grazing system under short intensively grazing management during the fall and spring to extend the winter wheat grazing season by approximately 60 d and can add as much as 52 kg of BW.